Update the pre-recorded messages in CertificateAuthoritiesTestCase and KeyStoresTestCase using the latest Boulder instance

The tests in CertificateAuthoritiesTestCase and KeyStoresTestCase simulate a mock Let's Encrypt server by using messages that were actually sent from Boulder (Let's Encrypt's testing server) to our ACME client. Wireshark was used to record the messages. The use of these recorded messages prevents us from having to integrate the complex Boulder setup into the Core testsuite.

Since these messages were pre-recorded just before the ACME protocol became an RFC, it would be good to update the pre-recorded messages used in these tests using the latest Boulder instance.